DNS Configuration and Management Manual (G06.27+, H06.05+, J06.03+)

DNS and BIND Basics
HP DNS Configuration and Management Manual—529432-003
A-7
The Resolution Process
the host name. (The default value of ndots is 1; therefore, if the input host name
contains one dot, the input host name is looked up as is before any domains are
appended to it.)
•
If the input host name contains a single component (that is, the host name without
any dots), and you have set up a host aliases file, BIND looks in your aliases file to
translate the alias to a fully qualified host name.
•
If the input host name does not end with a dot, BIND looks up the input host name
with domain names appended to the host name. You can configure the domain
names that BIND appends to the host name using the following methods:
°
The search option in the /etc/resolv.conf file.
°
The domain option in the /etc/resolv.conf file.
The
domain option specifies the local domain. If you use the domain option, BIND
searches only the specified domain to resolve the host names. BIND uses the
domain
option for host name lookups only if you do not specify the
search option.
If you use both the
domain and search options in the /etc/resolv.conf file (or
RESCONF file), only the option that appears last is used and the previous option is
ignored. Therefore, do not use both the options
domain and search in the resolver
configuration files.
See the
TCP/IPv6 Configuration and Management Manual for information about the
RESCONF file (the Guardian version of resolv.conf) and the
Open System Services
Management and Operations Guide for procedures to create a symbolic link to the
RESCONF file.
How the Resolver Functions
A resolver is a set of procedures called by any process that needs to ask questions of
a DNS server. Programs running on a host that need information from the domain
name space use the resolver. These programs are sometimes running on the same
system as the name server.
Resolvers question the DNS server, based on the configuration in /etc/resolv.conf. This
configuration tells the resolver whether to ask DNS look in /etc/hosts. So the resolver
could actually get information about hostname and IP address using DNS or the
/etc/hosts file.
The resolver handles the following tasks:
•
Builds a list of possible absolute domain names in case the requested name is a
relative domain name.
•
Queries the name server locally or on a remote host configured in /etc/resolv.conf
to translate the domain name into IP address(es). The resolver retransmits the
packet, possibly to another name server, if the queried name server does not
respond